In at least one process for the gasification or partial oxidation of coal or similar carbonaceous materials at elevated temperatures, the hot gaseous reaction zone product, termed synthesis gas, contains molten or solid particles variously described as flyslag or flyash. The product gas is passed from the reaction zone to sequential quench, cooling, and purification zones before being of sufficient purity or quality for use or sale.
The molten "slag" or "ash" particles represent a significant problem in the carrying out of the process, since they must be rendered harmless and/or removed in order to avoid plugging of the process zones and inevitable shutdown of the process. A number of techniques have been developed to prevent such situations from developing. For example, U.S. Pat. No. 4,149,859, incorporated herein by reference, describes a technique in which cool recycle product gas and an aqueous suspension are injected into the product gas to quench and cool the gas and solidify the molten particles in the gas. Nevertheless, because the walls of the quench or cooling zone or zones in contact with the product gas are cooled, such as by steam or water, and thus are at a temperature below that of the gas and the molten particles, deposition and buildup of ash or slag on the walls may occur over a period of time. A technique for removal of such deposits, without requiring shutdown of the process, might have great economic value. The invention concerns such a procedure.